632 



SCIENCE. 



[N. S. Vol. XVIII. No. 463. 



its seriousness on the part of the responsible 

 authorities. 



During the last few months the Field 

 Columbian Museum of Chicago has issued a 

 number of papers, some of them describing 

 new species and new genera, which bear date 

 ' June, 1903,' but which were not issued till 

 late in August or early in September. In 

 some instances the authors' separata were not 

 delivered to them till August 20. In one 

 case at least there is internal evidence to show 

 that the paper, dated ' June 1, 1903,' could 

 not have been even printed till some time in 

 July, since reference is made by the author 

 to the July, 1903, number of the American 

 Journal of Science, which was not published 

 till July 1 or 2. 



I am authoritatively informed that the au- 

 thors are in no way responsible for the dates, 

 or anything else, on the title pages of these 

 brochures, and hence the responsibility for the 

 antedating of papers which contain descrip- 

 tions of new genera and species by from 

 eight to ten weeks rests higher up. Presum- 

 ably it is sufficient to call attention to the mat- 

 ter to have the fault promptly remedied. 



J. A. Allen. 



THE 87-DAY PERIOD IN AURORAS AND ITS CON- 

 NECTION WITH SUNSPOTS. 



To THE Editor of Science : During the last 

 few months in New England there has been an 

 interesting example of the tendency of auroras 

 to return after intervals of 27 days. The re- 

 port of the New England ' Climate and Crop 

 Service ' shows that auroras were observed in 

 New England on July 25 and 27, the 26th 

 being rainy. Twenty-seven days later auroras 

 were observed on August 21 and 22. The next 

 return of the twenty-seven-day period was 

 September 17 to 19. General rain fell on 

 September 17, but aiiroras were observed on 

 the 18th and 19th. Twenty-seven days later 

 was October 14 to 16. Auroras were observed 

 on the 13th and possibly on subsequent dates 

 (the reports are not yet in). 



Another group of auroras began on August 

 26, was observed again on September 21 and 

 was due on October 19. 



Each of these auroral displays was con- 

 nected with sunspot activity and may have 

 preceded the first appearance of the spot. A 

 fine group of sunspots crossed the surface of 

 the sun next the earth on October 5 to 17, pass- 

 ing the sun's meridian about October 13. A 

 second smaller isolated sjjot crossed the sun's 

 meridian on October 18 or 19. 



About November 1 a very large sunspot 

 crossed the meridian of the sun next the earth 

 and with it apparently began a new series of 

 auroras which were very brilliant on the early 

 morning of November 1 and again on the 

 evening of the same day. 



According to the theory of Arrhenius, which 

 has much to sustain it, auroras are caused by 

 small highly electrified particles of matter 

 carried outward from the sun 1^;^ the pressure 

 of light when the sun is in a high state of 

 activity. These particles are intercepted by 

 the earth's atmosphere and from them is de- 

 rived the electrical charge which gives rise to 

 auroras and naagnetic currents (' Lehrbuch der 

 kosmischen Physik,' page 920). 



The twenty-seven-day period in the aurora 

 arises from the fact that it takes twenty-seven 

 days for a center of disturbance on the sun to 

 rotate around and face the earth in the same 

 relative position again. The period is not a 

 permanent one, the disturbance at any given 

 point lasting usually only for a few solar rota- 

 tions, and is then displaced by a disturbance 

 at some other part of the sun with which 

 another series of auroras is connected. 



There is, however, a twenty-seven-day period 

 of auroras connected with the siderial 

 revolution of the moon. This, however, is of 

 minor importance and can only be detected by 

 a long series of averages (American Journal 

 of Science, Vol. V., 1898, p. 81). 



If the auroras described here were of solar 

 origin they were probably visible over a large 

 part of the northern and southern hemi- 

 spheres. Some of them were very brilliant. 

 The aurora of August 21 was described in the 

 Popular Science Monthly, Vol. LXIIL, pp. 

 563-564, by A. F. A. King, and in Vol. LXIV., 

 pp. 87 and 88, by Alexander Graham Bell. 

 Henry Helm Clayton. 



